My son was in a crash the other day in a group ride. The handle bars twisted to one side and before I got there to help out, another rider straightened his bars out for him. The issue is that it is a carbon fiber steerer. I'm imagining that there is probably some scratching on the steerer. Are these things tough enough to take that kind of abuse, or should it be examined by a shop? He hasn't ridden it since and his injuries were minor.

You will ultimately have to make the decision if its trash. I think you should disassemble and inspect. There probably will be marks on the steerer tube. If the marks on the surface, perhaps the clearcoat is just damaged and not a big deal. If its gouged the carbon may be compromised. If there is any doubt, show a mechanic you trust.

Ive been riding carbon seatposts for years. At first I was concerned about clear coat damage where the frame seat post clamps to the post. I used to take nail polish and "repair" whenever I was maintaining the bike. Now, years later, I dont bother with the clear nail polish - its just a hassle. I think we dont give enough credit to how strong CF components are and how well they stand up to surface defects.

I had a carbon steerer tube that was getting dented from a sharp, inside edge of the stem. I didnt notice until months after installing. I removed a few spacers and filed down the stem sharp edge so that the dent, was out of the high stress area. I feel comfortable using the fork now that I addressed the issue, but I dont think I would continue riding the fork if the dent was still in the high stress area and the sharp edge was still banging on the steerer as I bounced down the road...

On the other hand, is a fork failure worth saving $300? Probably not, but Im cheap that way!

Can't tell without seeing , careful inspection.. take stem off and look,
should just have spun around the steerer ,
but if there was some burrs in the stem, or dirt, in there [back of the stem gap?]
the grit may have made it's mark..

Bike's in the shop right now. We'll see what they say. Meanwhile, I'm pricing forks!